The principal objective of the nursing profession is to provide evidence-based and competent care mainly based on humanitarian and ethical principles. Ethical care is contingent on a proper level of moral reasoning, which can be categorized into pre-conventional, conventional and post-conventional reasoning. At the pre-conventional level, individuals are mostly self-oriented and prefer obedience to avoid blame. At the conventional level people apply laws and social principles to decision-making, and at the post-conventional level they try to guide their actions and behaviors with regard to ethical principles and make humanist and ethical decisions. This study aimed to assess the level of moral reasoning in nurses and nursing students by providing an analysis of the existing literature on moral reasoning.For the purpose of this study, we conducted an extensive search of the papers published between 1980 and 2014 on international electronic databases including Scopus, Google scholar, Science Direct, PubMed, Proqust and Elsevier. We also reviewed papers published between 1985 and the autumn of 2014 on Persian electronic databases Sid, Magiran and Iran Medex. A broad range of search keywords were used such as: ethical growth, moral growth, ethical development, moral development, ethical reasoning, moral reasoning, nurse, and nursing student. In total, 35 studies were reviewed at this stage.Based on the results of the above-mentioned studies, most nursing students and nurses reason at the conventional and post-conventional level, and nursing students reason at a higher ethical level in comparison with nurses. We also found that teaching ethical concepts helps improve ethical reasoning, and that an inverse relationship exists between clinical experiences and ethical reasoning.Although in most studies, the level of moral reasoning in nursing students and nurses was found to be at the conventional and post-conventional level, this is not enough to provide superior professional care. It is therefore essential to apply the necessary measures such as improving clinical environments and the ethical education system to further promote the reasoning ability of nurses and nursing students, so that they can make their decisions based on ethical principles and at the post-conventional level